I was looking at purchasing the Rio Deep 6 WF6S6 however I will go with your suggestion (Rio Deep 7 WF7S7) knowing I should not have a problem casting it with a Helios 6 weight.

Also, could you please help with suggesting the best suitable lines for the below tasks:
• floating line for a size 12-16 tungsten weighted nymph and glo-bug rig?
• intermediate sinking line for stripping smelt/streamer patterns?